This Zucchini Gratin with tomatoes, breadcrumbs, garlic, parmesan cheese, and fresh basil is an easy, healthy, and delicious vegetarian side dish, perfect for using up your garden veggies.

round baking dish with tomato zucchini gratin topped with grated cheese, with a wood serving spoon.

Why You’ll Love This Zucchini Gratin

Zucchini Gratin is a celebration of late-summer abundance: tender zucchini, ripe tomatoes, fresh basil, and garlic layered into a simple yet elegant side dish. We keep it on the lighter side and skip the cream, using only a light sprinkling of Parmesan.

As a chef, I’ve spent years creating recipes with seasonal, locally sourced produce, but starting my own garden has brought a whole new level of appreciation. This gratin is one of my favorite ways to showcase what’s growing just outside my door. It comes together effortlessly and pairs beautifully with many meals, allowing the freshness of the ingredients to truly shine.

Zucchini Gratin Ingredients

heirloom tomato in front of more garden tomatoes and green zucchini.
  • Zucchini: Use fresh green zucchini and yellow squash from your garden or local farmers’ market for optimal flavor!
  • Tomatoes: Use tomatoes that are easy to slice, like heirloom tomatoes, beefsteak, Roma, or tomatoes on the vine.
  • Bread: For best results, use slightly stale bread to make the breadcrumbs, like leftover sourdough bread! While you can use panko, homemade breadcrumbs are so much better!
  • Parmigiano Reggiano: We highly recommend the sharp, tangy Parmigiano Reggiano but of course, many other kinds of cheese will work just as beautifully.
  • Fresh herbs: Use thyme, oregano, and basil for a fresh, summery taste.
  • Red pepper flakes: Optional, but adds a nice hint of heat.
  • Red wine vinegar: Adds a touch of acidity that balances all of the flavors.
  • Garlic cloves and large shallot: For aromatic, savory depth. If you want to boost the aromatic flavor, layer in onions.
parmigiano reggiano block with fresh herbs.

What is a gratin?

A gratin is basically a baked dish topped with seasoned breadcrumbs and cheese. This Tomato Zucchini Gratin is an elegant and simple way to honor end-of-summer garden tomatoes and to use up more of the ever-abundant zucchini.

How to Make Zucchini Gratin

1. Toast the breadcrumbs. Preheat the oven to 400F. Hand tear the bread to form coarse crumbs (or quickly pulse in a food processor). Transfer to a baking sheet and bake for 3-5 minutes, until dried out.

torn bread crumbs on a parchment-lined baking sheet.

2. Season the breadcrumbs. Toss the breadcrumbs in a medium bowl and stir with 2 tablespoons of olive oil, thyme, oregano, salt, black pepper, red pepper flakes, and parmesan.

bowl with torn bread crumbs, minced herbs, grated cheese, and wood spoon.

3. Arrange tomato and zucchini. In a shallow baking dish, alternate placing tomato and zucchini slices. If using a round baking dish, arrange the slices around the edge and place any remaining zucchini in a smaller circle in the center. Season with salt and pepper.

round baking dish with alternating slices of tomato and zucchini.

4. Pour marinade over top. Whisk the remaining olive oil, red wine vinegar, minced garlic, and shallot. Pour over the dish.

5. Top with breadcrumbs. Sprinkle the breadcrumb mixture evenly over top.

6. Bake. Bake the zucchini gratin for 20 minutes or until the zucchini is tender, the cheese is melted, and the breadcrumbs are toasted. Tent with foil, to bake longer.

7. Garnish. Garnish with fresh basil leaves and serve warm or at room temperature.

round baking dish with tomato zucchini gratin with wood serving spoon, blistered cherry tomatoes, and grated cheese.

Chef’s Tips

  1. Hand-tear the bread. This makes the pieces craggy, allowing the olive oil, herbs, and cheese to hang on more easily.
  2. Cut even slices. Make the tomato and zucchini slices uniform for even baking.
  3. Use stale bread. This is ideal for creating extra crispy breadcrumbs!
  4. Grease the baking dish. For easier serving, spray the baking dish with cooking spray.
  5. To make it creamier or cheesier: For a heartier dish, feel free to layer in gruyere cheese or pour a creamy sauce over top, like a roux made with heavy cream or butter and flour.

Storage

Store leftover zucchini gratin in an airtight container in the refrigerator for up to 4 days. Let cool completely before storing. Reheat in a 350F oven, uncovered, for 15-20 minutes. Keep in mind, the vegetables will release their juices over time, so this is best enjoyed fresh!

FAQs

What is the difference between au gratin and gratin?

They are essentially the same. Au gratin refers to a dish with a crispy topping of cheese and breadcrumbs. Gratin refers to the crispy topping itself.

What kind of cheese goes well with zucchini?

The best cheese for this zucchini gratin is sharp, tangy Parmigiano Reggiano, but any sharp and salty white cheese works well.

What seasonings go well with zucchini?

Fresh herbs like thyme, oregano, and basil enhance the summery taste of zucchini.

Serving Suggestions

The vegetarian gratin makes a perfect vegetable side dish for dinner, pairing nicely with most grilled or roasted fish and meat. The tomato gratin is also a beautiful addition to brunch with poached eggs, steamed greens, and wild rice-or for lunch or a light dinner!

round baking dish with tomato zucchini gratin with wood serving spoon, blistered cherry tomatoes, and grated cheese.

More Zucchini & Tomato recipes

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A simple recipe for Tomato Zucchini Gratin with breadcrumbs, parmesan and fresh basil. A quick and easy vegetarian side dish! #gratin #tomatogratin #zucchinigratin

Easy Zucchini Gratin

5 Stars 4 Stars 3 Stars 2 Stars 1 Star 4.9 from 9 reviews
  • Author: Tonia Schemmel | Feasting at Home
  • Prep Time: 20
  • Cook Time: 20
  • Total Time: 40 minutes
  • Yield: 6
  • Category: side dish
  • Method: baked
  • Cuisine: Mediterranean
  • Diet: Vegetarian
Print Recipe

Description

A simple recipe for Zucchini Gratin with tomatoes, breadcrumbs, garlic parmesan, and fresh basil. A quick and easy vegetarian side dish that’s cozy and warming.

Ingredients

Units Scale
  • 3 slices (3 oz) bread
  • 4 tablespoons olive oil, divided
  • 1 tablespoon fresh thyme, chopped fine
  • 1 tablespoon fresh oregano, chopped fine
  • 1/2 teaspoon salt
  • 1/4 teaspoon pepper
  • 1/4 teaspoon red pepper flakes (optional)
  • 1 1/2 oz (3/4 cup) Parmigiano Reggiano, grated
  • 2 lbs tomatoes, sliced 1/2 inch thick (4-5 medium tomatoes)
  • 1 lb zucchini, sliced 1/4 inch thick ( 2 medium zucchini)
  • salt and pepper to taste
  • 1 tablespoon red wine vinegar
  • 2 large cloves garlic, minced
  • 1 tablespoon shallot, diced
  • 1/2 cup fresh Basil leaves

Instructions

  1. Preheat oven to 400F
  2. Hand tear bread to form coarse crumbs (or quickly pulse in food processor).  Place on a sheet pan and bake at 400 degrees for 3-5 minutes, until dried out.
  3. Toss toasted bread, 2 tablespoons of olive oil,  thyme, oregano, salt, black pepper, red pepper flakes, and parmesan together in a bowl.  Set aside.
  4. Alternate tomato and zucchini slices in a shallow baking pan.
  5. Season with salt and pepper.
  6. Whisk together remaining olive oil, red wine vinegar, minced garlic and shallot.  Pour over tomatoes and squash.
  7. Top evenly with bread crumb mixture.
  8. Bake on the middle rack at 400°F for 20 minutes, or until the zucchini is fork-tender and the breadcrumbs are toasty. If it is getting too dark, tent with foil. 
  9. Tear basil leaves on top and serve warm or at room temperature.

Notes

Leftovers will keep up to 4 days in an airtight container in the refrigerator. 

Nutrition

  • Serving Size:
  • Calories: 181
  • Sugar: 4.2 g
  • Sodium: 390.1 mg
  • Fat: 11.8 g
  • Saturated Fat: 2.5 g
  • Carbohydrates: 15.9 g
  • Fiber: 2.9 g
  • Protein: 5 g
  • Cholesterol: 6.1 mg

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Comments

  1. I’ve made a few things from your website and they are all so fresh and tasty and this is no exception, it’s absolutely delicious! I made it as per the recipe and it came out perfectly. I served mine with a little wild salmon and crumbled feta. I think it probably sings more if your veg are at their best and in season. Yummy!

    Reply

  2. This is my first time ever writing a comment about a recipe. I always tell my kids always take things with a grain of salt of things that are posted in internet. However, your website and the recipes you share are TOP NOTCH no changes needed. Our whole family devoured the meal tonight. Since i didnt have red wine vinegar used balsamic vinegar and aged cheddar cheese. My kids who usually make a fuss about tomatoes just loved them in this recipe.

    Reply

  3. So incredibly delicious and pretty! I made it in my cast iron skillet. There was more liquid than I liked initially, but the crumbs eventually soaked up the excess and it was even better the next day! I am going to make/add more of the crumb mixture next time.

    Reply

  4. Absolutely loved this recipe. So simple but so flavoursome and juicy. I found that the the different textures of the soft roasted veg and the crunchy cheesy bread crumbs elevate the dish, creating a very interesting experience. I had it with smoked mackerel for dinner and definately plan to cook it again. Thanks for yet another great recipe!

    Reply

  5. We loved this…a couple of comments. First, it took much longer to bake than recipe stated. Bread crumbs browned well before veggies were cooked, so I lightly covered with foil and left it in for almost another 20 minutes. Still the zucchini was partially crispy- not soggy at all. Also, I used panko bread crumbs- so much easier than making your own and they are so light and crispy. A great recipe- especially for August-September when zucchini can be plentiful and tomatoes at their best!!

    Reply

    1. Thanks for your feedback Cindy. Was your zucchini sliced thin? Also sometimes if the squash is a little older, or on the larger size, it can take longer to cook as there is not as much moisture. Glad you made it work though!

      Reply

  6. Can this be made ahead and reheated? I need a side dish to feed 14 for a family dinner. I plan to 2.5 of this recipe the day before. Can I just cover and reheat it before dinner the next day? Also do you think it will all fit in 2 9×13 baking pans?
    Thanks for your input.
    BTW – Long time reader; first time commenter. I LOVE your blog. I usually make at least one recipe a week. They’re always awesome!

    Reply

    1. I have not tried this Annie but it should be ok. I think it will just be extra juicy, which may just be delicious if you have extra bread to sop it up. Seems like it would fit in 2 9×13’s- guessing about that.

      Reply

      1. Awesome. Thank you Tonia! I’ll let you know how it goes. Also serving the blistered tomato & saffron risotto.

        Reply

      2. Well I made both the Blistered Tomato Saffron Risotto and the Tomato Zucchini Gratin the day of the family dinner party (right before serving in fact) and they were both delicious! My Italian father in law had 3 servings of the Risotto! There were plenty of leftovers. We reheated the Gratin and it re-crisped the torn bread topping beautifully. It was not extra saucy. Next time I’ll make it the day before and re-warm prior to serving.
        Thanks for the lovely recipes!

        Reply

  7. Having recently spring cleaned both pantry and fridge, I took all sorts of liberties with the recipe (using leftover stuffing cubes from Thanksgiving 2022 for the bread crumbs, subbing mozzarella for parm, cherry tomatoes for summer tomatoes, etc. The only note I introduced was to sub the leftover oil from a jar of sun-dried tomatoes I had hanging in my fridge for some of the olive oil. Husband actually volunteered a compliment at dinner – “this is really good.” Surprised my shoes off – he is not a huge fan of summer squashes for textural reasons. Wildly adaptable template. Thank you! (I did use fresh basil)

    Reply

  11. The flavors and textures of this dish are lovely. It has gotten rave reviews. I’ve made it twice so far, and have found that the zucchini cooks better if sliced thinner than 1/4 inch and when cooked for 25 minutes.

    Reply

  13. This dish was amazing. Everyone raved about how good it was. Only had a single helping leftover. The next day I added some cheddar cheese and it was gone.

    Reply

  14. You didn’t add squash to the ingredients list. ;-; I didn’t get the squash ;-; I don’t have squash in my meal ;-; oof. No worries next time I’ll just add a mental note also how much squash would I need

    Reply

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